Ideas for rotary cutter build

[deanwerden]

I would like to build a rotary cutter for my compact tractor , 4 feet wide but would like to use 2, 2ft blades to keep the length down, I always though a compact with a 4ft rotary cutter looked ridiculous. My idea was to either buy one gearbox and connect it to the blades with either sprockets or belts. I am wondering if a gearbox could be eliminated with the use of a double or triple v belt arrangement that wraps up 90 degrees with a hub for the pto shaft. This cutter will be used mostly for tall grass with the occasional sapling probably no more than 1". I have cut the same area of long grass with my mid mower before fully raised and It did OK but was slow going. I just see no reason why a double belt arrangement wouldn't work as my mid mower only uses one belt and will stall the engine out before the belt slips (as far as I can tell).

My idea is to use 2 flanged bearings spaced a few inches apart for the blade shafts, bottom will have a hub for blades and top obviously a pulley . I will then build a small platform where I can mount 2 more pillow blocks with a small stub shaft that will have a pulley on the rear and the front will have the pto shaft facing the rear of the tractor. Then I will obviously need a few idler pulleys to make the turn 90 degrees .

Thoughts? Any reason this kind of setup wouldn't work?

 

[rustyshakelford]

Sounds like a complex solution to a simple problem. 2-2' blades is probably larger than what would come on a 48" shredder? Those cutters are usually pretty compact anyways. What it sounds like your wanting to build is more like a rear finish mower but that can handle a 1" sapling. Have you used a 38" rotary cutter and don't like it or you just want a project to work on?

I really like the KISS method and to not reinvent the wheel

Brett

 

[flusher]

Buy a used 4-foot brush hog for a few hundred bucks and rebuild it to your specifications. You can sharpen the blade to give a cut like a riding mower or you can grind the cutting edge with a larger radius to cut brush.

 

[Shaneard]

Think you can realistically build something for less than $850? Here's a 4' mower at Agri-Supply for $849.99

4 Ft Finishing Mower, 3 Point Mower, Rotary Mower

Personally I think if you mow a 1" tree with anything with a 2' blade and a belt you will have bad results for your blade or your belt. My dad had a 5' 3 pt. hitch mower and every time he decided to mow the "thick" grass he would have to buy an expensive belt. If you want a 4' bush hog get a 4' bush hog, if you want a 4' mower get a 4' mower. I think you will have a lot of time, effort & money in something you can already buy for not a lot more or less than you will have in it doing it your self.

 

[deanwerden]

Sounds like a complex solution to a simple problem. 2-2' blades is probably larger than what would come on a 48" shredder? Those cutters are usually pretty compact anyways. What it sounds like your wanting to build is more like a rear finish mower but that can handle a 1" sapling. Have you used a 38" rotary cutter and don't like it or you just want a project to work on?

I really like the KISS method and to not reinvent the wheel

Brett

Yes you are correct I am essentially looking at building a rear finish mower that can take care of a few saplings in the way. Similar concept to the big 8'+ bush hogs that are sometimes a 2 blade design. I am going to build one either way just thought this design would take up less space both when in use and in storage.

 

[deanwerden]

Think you can realistically build something for less than $850? Here's a 4' mower at Agri-Supply for $849.99

4 Ft Finishing Mower, 3 Point Mower, Rotary Mower

Personally I think if you mow a 1" tree with anything with a 2' blade and a belt you will have bad results for your blade or your belt. My dad had a 5' 3 pt. hitch mower and every time he decided to mow the "thick" grass he would have to buy an expensive belt. If you want a 4' bush hog get a 4' bush hog, if you want a 4' mower get a 4' mower. I think you will have a lot of time, effort & money in something you can already buy for not a lot more or less than you will have in it doing it your self.

I am not looking for a finish mower I am looking to build a rotary cutter with a similar design to this

1 foot bushhog - Bing images

 

[jeff9366]

Buy a used 4-foot brush hog for a few hundred bucks and rebuild it to your specifications. You can sharpen the blade to give a cut like a riding mower or you can grind the cutting edge with a larger radius to cut brush.

Y E S .

 

[oldnslo]

If the blades are not allowed to free swing like a brush hog what happens when you hit more solid like a sapling? If going slow enough it will probably chew through it. If a little to solid what gives at that point? Blade bend, belts slip, stub shaft bends, etc..

 

[deanwerden]

If the blades are not allowed to free swing like a brush hog what happens when you hit more solid like a sapling? If going slow enough it will probably chew through it. If a little to solid what gives at that point? Blade bend, belts slip, stub shaft bends, etc..

the blades will be free swinging like bush hog

 

[Shaneard]

I am not looking for a finish mower I am looking to build a rotary cutter with a similar design to this

1 foot bushhog - Bing images

A bush hog has no belt. Mowers have belts. There are reasons for this. Good luck with whatever you decide!

 

[deanwerden]

If the blades are not allowed to free swing like a brush hog what happens when you hit more solid like a sapling? If going slow enough it will probably chew through it. If a little to solid what gives at that point? Blade bend, belts slip, stub shaft bends, etc..

I have been keeping my eye out for this mythical used 4 ft bush hog for 2 years and they are either 500 bucks and rotted to sh*t or new and $1400

 

[deanwerden]

A bush hog has no belt. Mowers have belts. There are reasons for this. Good luck with whatever you decide!

How about chains then?

 

[Shaneard]

How about chains then?

I would say there's a reason nobody has ever seen a bush hog with a chain on it other than to adjust the height or for guards.

 

[jb1390]

Yes you are correct I am essentially looking at building a rear finish mower that can take care of a few saplings in the way. Similar concept to the big 8'+ bush hogs that are sometimes a 2 blade design. I am going to build one either way just thought this design would take up less space both when in use and in storage.

You already have a MMM. You are essentially talking about building another, nearly identical mower to go on the back. If the MMM was not sufficient, not sure why moving it to the back would magically make it better. If you want a bush hog, buy a bush hog. If you are really bent on building it yourself, then build a bush hog. However, I would think your efforts would be better served building something that's not already commercially available on the cheap.

There are several reasons what you are talking about is different than comparing a 6' single to a dual spindle 8' cutter. the biggest difference is blade mass. Even an 8' cutter is spinning a lot of weight off each spindle. The blade momentum does most of the work for a bushhog. Trying to scale down an 8' cutter will require significantly reducing the rotating mass, which removes a significant amount of capability. I'm also not sure how you would make the blades swing in as small of a concept as you are thinking - and if you don't you will break things often.

Just buy a 4' bushhog if you have bushhog things to do.

Don't sweat the storage - many of them live outside. Mine does...... If you are really worried about getting it inside, they store pretty well standing up.

 

[CADplans]

The easiest DIY of a mower is to make the drive a car tire.
Mount the blades on a disk of steel,,, support the disk with a couple bearings.
Mount a car tire at 90 degrees to the disk, and PTO drive the car tire.
The inflation pressure of the tire controls the slip.

This design was used by many states for highway mowing for decades.
Then,,, they got flail mowers.

 

[bspeedy]

My neighbor just bought a 4-foot woods Brush Bull for 400 bucks. Great deal.

If you are going to build what is basically a rear finish mower, why not buy a cheap 4' or 5' finish mower and start from there?

 

[deanwerden]

Ok good info, The mass of the blades makes sense, I also like the tire driven set-up.

So can we at least agree that a 2 bladed bush hog style mower with heavy folding blades would at least be more successful in cutting tall grass than a mid mounted deck. The option of buying is well, not even an option. I can buy a 45hp gearbox for 120 bucks, might have 100 bucks in steel then misc bearings ect. I doubt I will have $500 into whatever I build. New is $1400 in Canada and I don't see any used ones within a 6 hour drive

Back to the drawing board I guess

 

[shaeff]

Too bad you're not closer to me, there's a 4' tow-behind model near me, it's rusty but mostly solid, for $150. Another one further down the CL page in really nice shape for $400.

 

[bcp]

Back to your no-gearbox belt drive mower idea, there used to be many more of these around. They seem to be out of style now.

















Bruce

 

[bspeedy]

Ok good info, The mass of the blades makes sense, I also like the tire driven set-up.

So can we at least agree that a 2 bladed bush hog style mower with heavy folding blades would at least be more successful in cutting tall grass than a mid mounted deck. The option of buying is well, not even an option. I can buy a 45hp gearbox for 120 bucks, might have 100 bucks in steel then misc bearings ect. I doubt I will have $500 into whatever I build. New is $1400 in Canada and I don't see any used ones within a 6 hour drive

Back to the drawing board I guess

Sorry - I'm all for ingenuity, but throwing away 500 dollars on something that is 90% the same as a cheap-o rear finish mower is not a good plan. 500 bucks will get you a great 4' bush hog that will actually work. I like to DIY, but sometimes it just doesn't make sense. Farm implements and trailers are two of those cases.